Hammer toe implant with expansion portion for retrograde approach

ABSTRACT

An implant for fusing adjacent bones is disclosed. The implant includes an elongate threaded member and a flexible portion extending from the elongate threaded member. The flexible portion includes a plurality of prongs configured to be reversibly compressed toward an axis defined by the elongate threaded member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/350,663, which was filed on Jun. 2, 2010, and to U.S. ProvisionalPatent Application No. 61/434,491, which was filed on Jan. 20, 2011, theentireties of which are herein incorporated by reference.

FIELD OF DISCLOSURE

The disclosed system and method relate implants. More specifically, thedisclosed system and method relate to installing an implant for treatinghammer toe.

BACKGROUND

Hammer toe is a deformity of the toe that affects the alignment of thebones adjacent to the proximal interphalangeal (PIP) joint. Hammer toecan cause pain and lead to difficulty in walking or wearing shoes. Ahammer toe can often result in an open sore or wound on the foot. Insome instances, surgery may be required to correct the deformity byfusing one or both of the PIP and distal interphalangeal (DIP) joints.

The most common corrective surgery includes the placement of a pin orrod in the distal, middle, and proximal phalanxes of the foot to fusethe PIP and DIP joints. The pin or rod is cut at the tip of the toe,externally of the body. A plastic or polymeric ball is placed over theexposed end of the rod, which remains in the foot of the patient untilthe PIP and/or DIP joints are fused in approximately 6 to 12 weeks. Thisconventional treatment has several drawbacks such as preventing thepatient from wearing closed toe shoes while the rod or pin is in place,and the plastic or polymeric ball may snag a bed sheet or other objectdue to it extending from the tip of the toe resulting in substantialpain for the patient.

Another conventional implant includes a pair of threaded members thatare disposed within adjacent bones of a patient's foot. The implants arethen coupled to one another through male-female connection mechanism,which is difficult to install in situ and has a tendency to separate.

Yet another conventional implant has body including an oval head and apair of feet, which are initially compressed. The implant is formed fromnitinol and is refrigerated until it is ready to be installed. The headand feet of the implant expand due to the rising temperature of theimplant to provide an outward force on the surrounding bone wheninstalled. However, the temperature sensitive material may result in theimplant deploying or expanding prior to being installed, which requiresa new implant to be used.

Accordingly, an improved implant for treating hammer toe is desirable.

SUMMARY

An implant for fusing adjacent bones is disclosed. The implant includesan elongate threaded member and a flexible portion extending from theelongate threaded member. The flexible portion includes a plurality ofprongs configured to be reversibly compressed toward an axis defined bythe elongate threaded member.

An implant system is also disclosed. The implant system includes animplant comprising an elongate threaded member and a flexible portionextending from the elongate threaded member. The flexible portionincludes a plurality of prongs configured to be reversibly compressedtoward an axis defined by the elongate threaded member. A core pin fordriving the implant into bone includes an elongate body having a pointedtip at one end and a fin disposed at an opposite end. The fin is sizedand configured to be received within a slot defined by the prongs of theimplant. A tube defines a passageway extending from an implant engagingend to a core pin engaging end and being sized and configured to receivethe prongs of the implant and a first portion of the core pin therein.

Also disclosed is a method of connecting adjacent bones. The methodincludes forming an incision to gain access to a joint between first andsecond bones, flexing the first and second bones such that the bones aredisposed at an angle from one another, and inserting a pointed tip of acore pin extending from a first end of a tube into a first end of afirst bone until a tip of an elongate threaded member of an implantextending from and at least partially disposed within a second end ofthe tube is received within an intramedullary channel formed by the corepin and tube. The first end of the first bone is closer to the secondbone compared to a second end of the first bone. The first and secondbones are repositioned such that they are approximately linearly alignedwith each other. The core pin is rotated in a first direction to drivethe elongate threaded member into the second bone. The core pin isdecoupled from its engagement with the implant, and the core pin andtube are withdrawn from the first bone to disengage the second end ofthe tube from a flexible portion of the implant including a plurality ofprongs. The plurality of prongs outwardly flex to contact the first bonewhen disengaged from the second end of the tube.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bemore fully disclosed in, or rendered obvious by the following detaileddescription of the preferred embodiments of the invention, which are tobe considered together with the accompanying drawings wherein likenumbers refer to like parts and further wherein:

FIG. 1A is an isometric view of an improved implant for treating hammertoe in an uncompressed or natural state;

FIG. 1B is an isometric view of the improved implant illustrated in FIG.1A in which the implant is in a compressed state;

FIG. 2 is a plan view of the improved implant for treating hammer toeillustrated in FIG. 1B;

FIG. 3 is an end view of the flexible portion of the implant taken alongline 3-3 in FIG. 2;

FIG. 4 is a sectional view of the implant taken along line 4-4 in FIG.2;

FIG. 5 is a cross-sectional view of the implant taken along line 5-5 inFIG. 2;

FIG. 6 is a side plan view of one example of driving wire for drivingthe implant illustrated in FIGS. 1A-5 into bone;

FIG. 7 is a sectional view of the driving wire taken along line 7-7 inFIG. 6;

FIG. 8 is an end view of the driving wire taken along line 8-8 in FIG.6;

FIG. 9 is an end view of the driving wire taken along line 9-9 in FIG.6;

FIG. 10 is a top side view of a handle configured to engage the drivingwire illustrated in FIG. 6;

FIG. 11 is a cross-sectional view of the body of the handle taken alongline 11-11 in FIG. 10;

FIG. 12 is a side view of the handle illustrated in FIG. 10;

FIG. 13 illustrates the flexible portion of the implant disposed withina blind hole defined by an engagement portion of the driving wire;

FIGS. 14A-B illustrate the middle and proximal phalanxes of a foot beingresected;

FIGS. 15A-15B illustrate the drilling through the middle and distalphalanxes of a foot;

FIG. 16 illustrates passing the trocar through the middle and distalphalanxes of a foot;

FIG. 17 illustrates a driving tool being disengaged from an end of thedriving wire coupled to an implant and being attached to an end of thedriving wire including a trocar tip;

FIG. 18 illustrates the implant coupled to an end of the driving wirebeing received within the intramedullary channel formed in the middlephalanx;

FIG. 19 illustrates the distal, middle, and proximal phalanxes beingaligned;

FIG. 20 illustrates the implant disposed within proximal phalanx;

FIG. 21 illustrates the implant disposed across the proximalinterphalangeal joint as the driving wire is withdrawn;

FIG. 22 is a plan view of one example of an assemblage of an implant, atube, and a driving core;

FIG. 23A is an isometric view of another example of a hammer toe implantin its natural or uncompressed state;

FIG. 23B is an isometric view of the hammer toe implant illustrated inFIG. 23A in its compressed state;

FIG. 24 is a cross-sectional view of the tube illustrated in FIG. 22taken along the length of the tube;

FIG. 25 is a plan view of one example of a driving core in accordancewith FIG. 22;

FIG. 26 is a cross-sectional view of the driving core taken along line26-26 in FIG. 25;

FIG. 27A illustrates the interface between the driving core and the tubeillustrated in FIG. 22 at a first stage of implanting the implant;

FIGS. 27B and 27C illustrate the interface between the blade of thedriving core and the implant disposed within the tube at the first stageof implanting the implant;

FIG. 28A illustrates the interface between the driving core and the tubeillustrated in FIG. 22 at a second stage of implanting the implant;

FIGS. 28B and 28C illustrate the interface between the blade of thedriving core and the implant disposed within the tube at the secondstage of implanting the implant;

FIG. 29A illustrates the interface between the driving core and the tubeillustrated in FIG. 22 at a third stage of implanting the implant;

FIGS. 29B and 29C illustrate the interface between the blade of thedriving core and the implant disposed within the tube at the third stageof implanting the implant;

FIG. 30A illustrates the interface between the driving core and the tubeillustrated in FIG. 22 at a fourth stage of implanting the implant;

FIG. 30B illustrates the interface between the blade of the driving coreand the implant disposed within the tube at the fourth stage ofimplanting the implant;

FIG. 31A is an isometric view of another example of a hammer toe implantin its natural or uncompressed state;

FIG. 31B is a side view of the hammer toe implant illustrated in FIG.31A;

FIG. 31C is an isometric view of the hammer toe implant illustrated inFIG. 31A in its compressed state; and

FIG. 31D is a side view of the hammer toe implant illustrated in FIG.31C.

DETAILED DESCRIPTION

This description of preferred embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description. The drawing figures are notnecessarily to scale and certain features of the invention may be shownexaggerated in scale or in somewhat schematic form in the interest ofclarity and conciseness. In the description, relative terms such as“horizontal,” “vertical,” “up,” “down,” “top,” and “bottom” as well asderivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,”etc.) should be construed to refer to the orientation as then describedor as shown in the drawing figure under discussion. These relative termsare for convenience of description and normally are not intended torequire a particular orientation. Terms including “inwardly” versus“outwardly,” “longitudinal” versus “lateral,” and the like are to beinterpreted relative to one another or relative to an axis ofelongation, or an axis or center of rotation, as appropriate. Termsconcerning attachments, coupling, and the like, such as “connected” and“interconnected,” refer to a relationship wherein structures are securedor attached to one another either directly or indirectly throughintervening structures, as well as both movable or rigid attachments orrelationships, unless expressly described otherwise. The term“operatively connected” is such an attachment, coupling or connectionthat allows the pertinent structures to operate as intended by virtue ofthat relationship.

Unless otherwise stated, all percentages, parts, ratios, or the like areby weight. When an amount, concentration, or other value or parameter isgiven as either a range, preferred range, or a list of upper preferablevalues and lower preferable values, this is understood as specificallydisclosing all ranges formed from any pair of any upper range limit orpreferred value and any lower range limit or preferred value regardlessof whether those ranges are explicitly disclosed.

Referring to FIGS. 1A and 1B, an implant 100 formed in accordance withone embodiment of the invention includes an elongate body 102 having athreaded portion 104 and a flexible portion 106, which are joinedtogether at an engagement portion 108. Implant 100 may be provided in avariety of lengths and widths for implantation in the distal and middlephalanxes of a foot. In one example, implant 100 has a length ofapproximately 2.1 centimeters (approximately 0.825 inches) and a maximumouter diameter of approximately 0.24 centimeters (approximately 0.094inches). Implant 100 may be formed from any material suitable forimplanting into living tissue including, but not limited to, stainlesssteel, nitinol, aluminum, polymer, or the like. Fabricating implant 100from nitinol, or another shape memory or super elastic alloy, mayadvantageously enhance resistance to movement of the implant whenpositioned in a foot, as described below.

Threaded portion 104 includes a plurality of threads 110 that taper to atip 112 for cutting into bone. In some embodiments, threaded portion 104has a length of approximately 1.3 centimeters (approximately 0.51inches) and a diameter of approximately 0.2 centimeters (approximately0.079 inches), although one skilled in the art will understand thatthreaded portion 104 may have other dimensions. For example, threadedportion 104 may have lengths of approximately 1 centimeter or 1.6centimeter, to list a couple of alternative lengths.

Flexible portion 106 includes a plurality of prongs 114 formed bylengthwise slots 116 defined in body 102. For example, flexible portion106 may include two, three, four or more prongs 114 formed by two slots116 orthogonally disposed from one another. One skilled in the art willunderstand that slots 116 may be disposed at other angles with respectto each other. In some embodiments, slots 116 extend approximately 0.57centimeters (approximately 0.224 inches) from end 118 of flexibleportion 106. One skilled in the art will understand that slots 116 mayhave a length that is less than half a length of flexible portion 106 orapproximately equal to the length of flexible portion 106. Each ofprongs 114 may include a taper section 120 that tapers from a firstdiameter, which may be 0.2 centimeters (approximately 0.079 inches) to asecond diameter of approximately 0.14 centimeters (approximately 0.055inches) over a length of approximately 0.18 centimeters (0.071 inches).Each taper 120 may terminate at an outwardly projecting anti-rotationalfeature 122, which may have a triangular cross-section geometry as bestseen in FIGS. 2 and 4.

Engagement portion 108 may have a circular cross-sectional area having aplurality of notches 124 as best seen in FIGS. 1 and 3. Each notch 124may include a pair of opposed side walls 126 separated by a bottom wall128. In some embodiments, notches 124 have a depth of approximately 0.03centimeters (approximately 0.012 inches) and a width of approximately0.1 centimeters (approximately 0.04 inches), although one skilled in theart will understand that number of notches 124 and their respectivedimensions may be varied. As best seen in FIGS. 2 and 3, notches 124 maybe formed at an angle with respect to the longitudinal axis defined byimplant 100 to create projections 130 having pointed edges 132 toenhance engagement with driving wire 200. In some embodiments, the anglemay be between 0 and 45 degrees with respect to the longitudinal axis ofthe implant 100, and particularly between 10 and 20 degrees with respectto the longitudinal axis defined by the implant 100, and even moreparticularly approximately 15 degrees with respect to the longitudinalaxis defined by the implant 100.

Implant 100 is configured to be installed using a driving wire 200 suchas the one illustrated in FIGS. 5-8. As shown in FIG. 5, driving wire200 has an elongate body 202 having a trocar end 204 and an engagementend 206. The driving wire 200 may have an overall length ofapproximately 10.16 centimeters (approximately 4 inches) and an outerdiameter of approximately 0.25 centimeters (approximately 0.098 inches),although one skilled in the art will understand that the dimensions ofthe driving wire 200 may be varied. Trocar end 204 has a pointed trocartip 208, which may include a small flat 210 that may extend approximate0.63 centimeters (approximately 0.25 inches) from the trocar tip 208.Driving wire 200 may be fabricated from any medically compatiblematerial suitably rigid for drilling through bone including, but notlimited to, stainless steel, steel, and aluminum to name a few.

Engagement end 206 defines a blind hole 212 having an internal diametersized and configured to receive the flexible portion of implant 100. Insome embodiments, the internal diameter of blind hole 212 isapproximately 0.21 centimeters (approximately 0.08 inches) and extendsapproximately 0.89 centimeters (approximately 0.35 inches) from tip 214of engagement end 206. As best seen in FIGS. 6 and 8, engagement end 206includes a plurality of tabs 216 separated by notches 218. Tabs 216 aresized and arranged to be received in notches 124 of implant 100, andnotches 218 are sized and arranged to receive projections 130 of implant100. For example, notches 218 may have a width of approximately 0.09centimeters (approximately 0.035 inches) and extend to a depth ofapproximately 0.05 centimeters (approximately 0.02 inches) from the tip214 of engagement end 206. Additionally, notches 218 may be formed suchthat sidewalls 220 are angled with respect to the longitudinal axisdefined by the elongate body 202. For example, the angle may be between0 and 45 degrees with respect to the axis, and more particularly between10 and 20 degrees.

One or more implants 100 of various sizes may be provided in a kit alongwith one or more driving wires 200 and a handle 300 such as the oneillustrated in FIGS. 9-11. As best seen in FIG. 10, handle 300 includesa circular body 302 that slidingly receives an elongate member 304having a pair of oppositely spaced retaining elements 314 disposed ateither end to maintain engagement between body 302 and elongate member304. Handle 300 may be formed from any material suitably rigid fordriving wire 200 and implant 100 into bone including, but not limited tostainless steel, steel, aluminum, polymer, or plastic to name a few.

Body 302 defines first and second apertures 306, 308, which extendthrough body 302 and intersect with one another. In some embodiments,apertures 306 and 308 may have different dimensions for engagingdifferently sized driving wires 200. For example, aperture 306 may havea radius of approximately 0.13 centimeters (0.05 inches) with the flat310 having a distance of approximately 0.21 centimeters (approximately0.08 inches) from the apex of the aperture 306 opposite flat 310, andaperture 308 may have a radius of approximately 0.16 centimeters(approximately 0.06 inches) with flat 312 having a distance ofapproximately 0.25 centimeters (approximately 0.1 inches) from the apexof aperture 308 opposite flat 312.

The method of installing an implant 100 via a retrograde approachbetween the proximal and middle phalanxes is now described withreference to FIGS. 13-20. One skilled in the art will understand thatthe method described herein may be applied to the middle and distalphalanxes or other adjacent bones. FIG. 13 illustrates the implant 100having its flexible portion 106 received within the blind hole 212defined by the engagement end 206 of the driving wire 200 as prongs 114are compressed towards one another. In this configuration, projections130 of engagement portion 108 of implant 100 are at least partiallyreceived within notches 218 of engagement end 206 of driving wire 200and threaded portion 104 of implant 100 having threads 110 extends fromthe tip 214 of engagement end 206.

To install the implant, a toe 400 is opened to provide access to a joint402 between a middle phalanx 404 and proximal phalanx 406, and middleand proximal phalanxes 404, 406 may be resected using a bone saw orother tool 450, as shown in FIGS. 14A and 14B. Engagement end 206 ofdriving wire 200, with implant 100 disposed within blind hole 212, maybe received within chuck 454 of a drill 452, and trocar end 204 ofdriving wire 200 may be driven retrograde into the middle of proximalsurface 410 of middle phalanx 404, as illustrated in FIGS. 15A and 15B.

Driving wire 200 is driven by drill 452 until trocar end 204 passesthrough middle phalanx 404 and distal phalanx 408 and out of distal tip412 of distal phalanx 408, as shown in FIG. 16. With trocar end 204extending from distal tip 412 of distal phalanx 408, chuck 454 of drill452 may be loosened and removed from engaging implant 100 and engagementend 206 of driving wire 200. Drill 452 or handle 300 may then engagetrocar end 204 of driving wire 200, as shown in FIG. 17.

Driving wire 200 is distally advanced until implant 100 is receivedwithin intramedullary channel 414 formed by driving wire 200, as shownin FIG. 18. With tip 112 of implant 100 received within intramedullarychannel 414, middle phalanx 404 and proximal phalanx 406 are linearlyaligned with each other, as shown in FIG. 19, and drill 452 or handle300 is used to turn driving wire 200 in a clockwise direction to advancethreads 110 of implant into proximal phalanx 406, as shown in FIG. 20.One skilled in the art will understand that threads 110 may also beleft-handed threads such that turning driving wire 200 in acounterclockwise direction advances threads 110 into proximal phalanx406.

With implant 100 secured across joint 402, driving wire 200 is retractedand turned in an opposite direction with respect to the direction inwhich it was turned to advance threads 110 into proximal phalanx 406while retracting driving wire . Rotating driving wire 200 in an oppositedirection while retracting it, e.g., distally advancing driving wire200, causes a camming action between angled tabs 216 of driving wire 200and the angle projections of implant 100 to assist in retracting driving200 from intramedullary canal 414.

Driving wire 200 may be fully retracted from intramedullary canal 414.The removal of driving wire 200 from intramedullary canal 414 releasesprongs 114 of implant 100, which were compressed within blind hole 212of driving wire 200. If implant 100 is formed from a shape memorymaterial such as, for example, nitinol, then prongs 114 may radiallyflex towards their natural or uncompressed state, as illustrated in FIG.21, such that an edge 122 a of anti-rotational feature 122 of prongs 114engages the adjacent bone.

FIGS. 22-30B illustrate another embodiment of an implant 500 having asimilar configuration to implant 100 in which like elements of implant500 have the same reference numerals as the elements of implant 100increased by 400. Engagement portion 508 has a circular cross-sectionalgeometry and includes one or more prominences 534 radially extendingfrom body 502. As best seen in FIGS. 27B, prominence or pin 534 issubstantially cylindrical with first and second flats 536, 538 formedthereon. Flats 536, 538 extend away from each other in approximatelynormal directions from point 540.

Although implant 500 is illustrated as having a substantially linearbody 502 in FIGS. 22-30B, one skilled in the art will understand thatthe implant may have an angled body, such as implant 800 illustrated inFIGS. 31A-31D. Like elements of implant 800 have the same referencenumerals as the elements of implant 500 increased by 300. As best seenin FIG. 31D, threaded portion 804 and flexible portion 806 of implant800 extend from engagement portion 808 at angle with respect to eachother. In some embodiments, the angle between a central axes defined bythreaded portion 804 and flexible portion 806 is between approximately145° and 180°. In some embodiments, the angle between the central axesdefined by threaded portion 804 and flexible portion 806 of implant isbetween approximately 160° and approximately 175°. In some embodiments,the angle between the central axes defined by threaded portion 804 andflexible portion 806 of implant is between approximately 170°. However,one skilled in the art will understand that other angles are possible.

The one or more prominences 534, 834 of engagement portion 508, 808 ofimplants 500, 800 are configured to be engaged by implant engaging end602 of insertion tube 600 as illustrated in FIGS. 22 and 27B. Turningnow to FIG. 24, driving tube 600 has a substantially cylindrical andhollow body 604 and includes a driver core engaging end 606 that definesan opening 608 and is disposed opposite implant engaging end 602, whichdefines opening 610. Implant engaging end 602 defines a correspondingnumber of slots 612 as the number of prominences 534 that outwardlyextend from implant 500, 800. Slot 612 inwardly extends from implantengaging end 602 and includes a notch 614 that is sized and configuredto receive pin 534, 834 therein. Tab 616 of driving tube 600, whichdefines notch 614, engages flat 538, 838 of pin 534 for preventingrelative axial movement between implant 500, 800 and driving tube 600when prominence 534, 834 is received within notch 614.

Another slot 620 is disposed adjacent to driver core engaging end 606 ofdriving tube 600. As best seen in FIGS. 24 and 27A, slot 620 extends ina direction that is parallel with respect to a longitudinal axis definedby driving tube 600 and includes a pair of extensions 622-1 and 622-2(collectively referred to as “extensions 622”) that extend in adirection that is substantially orthogonal to the axis defined bydriving tube 600. Opening 608 has a diameter that is capable ofreceiving a portion of driver core 700 therein.

FIGS. 25 and 26 illustrated driver core 700 that includes an elongatebody 702 having a first end 704 comprising a fin 706 and a second end708 comprising a trocar tip or drill tip 710. A first portion 712 ofdriver core 700 has a cross-sectional diameter that is a smaller than asecond portion 714 of driver core 700 to define a ledge or step 716 andsuch that first portion 712 may be received within driving tube 600. Insome embodiments, second portion 712 of driver core 700 has an outerdiameter that is approximately equal to an outer diameter of driver corebody 702, although one skilled in the art will understand that secondportion 714 may have a diameter that is larger or smaller than an outerdiameter of driver core 702. Fin 706 has a width such that fin 706 maybe received within slots 516, 816 of implant 500, 800 as best seen inFIGS. 27B and 27B. Driver core 700 defines a hole 718 (FIG. 25) alongthe length of the first portion 712, which is sized and configured toreceive a dowel pin 720. In some embodiments, dowel pin 720 is sized tobe received within hole 718 in a press fit engagement.

To create the assemblage illustrated in FIG. 22, prongs 514 arecompressed from their natural position in which they outwardly extendaway from a longitudinal axis defined by implant 500 as illustrated inFIG. 23A to a compressed position as illustrated in FIG. 23B. Withprongs 514 compressed, flexible portion 506 of implant 500 is insertedinto opening 610 of driving tube 600 (FIGS. 27B and 27C). As flexibleportion 506 is inserted into opening 610, prominence 534 is receivedwithin slot 612 and within notch 614 by rotating implant 500 withrespect to driving tube 600 (FIG. 27B), or vice versa. Implant 800 maybe inserted into driving tube 600 in a similar manner except that body802 of implant 800 is also elastically bent such that body 802 ofimplant 800 is substantially linear. In order to achieve such elasticdeformation, implant 800 may be formed from a superelastic material suchas, for example, nitinol or other shape memory alloy.

First portion 712 of driver core 700 is inserted into opening 608 ofinsertion tube 600. As first portion 712 is received within driving tube600, fin 706 is aligned with and received within slots 516, 800 ofimplant 500, 800 disposed at the opposite end of driving tube 600 (FIGS.27B and 27C). With driver core 700 disposed within insertion tube 600,dowel pin 720 is inserted into hole 718, which is visible through slot620 and/or one of extensions 622 as shown in FIG. 27A. Dowel pin 720secures driver core 700 within driving tube 600, but permits relativemotion between driver core 700 and driving tube 600 as dowel pin 720 mayslide within slot 620 and extensions 622.

With implant 500, driving tube 600, and driver core 700 assembledtogether, the resultant assemblage may be used to install implant 500within the joint between the proximal and middle phalanxes via aretrograde approach. For example, access to joint 402 between middlephalanx 404 and proximal phalanx 406 is obtained by making an incisionin toe 400. A bone saw or other tool 450 may be used to provide flatsurfaces on the ends of middle and proximal phalanxes 404, 406.

Implant engaging end 602 and threaded portion 504, 804 of implant 500,800 are received within chuck or pin driver 454 of drill 452 such thattrocar tip 710 of driver core 700 is exposed and may be driven intoproximal surface 410 of middle phalanx 404. As drill 452 rotates in aclockwise direction (or counterclockwise depending on the orientation ofextensions 622 and notch 614), dowel pin 720 is received withinextension 622-1 and the motion of driving tube 600 is translated todriving core 700. Drill 452 drives driving tube 600 and driving core 700until trocar tip 710 emerges from the distal tip 412 of distal phalanx408 such trocar tip 204 extending from distal tip 412 in FIG. 16.

With trocar tip 710 extending from distal tip 412 of distal phalanx 408,chuck or pin driver 454 is loosened and moved from engaging implantengaging end 602 of driving tube 600 to engaging second portion 714 ofdriver core 700. The assemblage of implant 500, 800, driving tube 600,and driver core 700 are distally advanced until tip 512 of threadedportion 504, 804 is received within intramedullary channel 414 formed bytrocar tip 710. With tip 512 disposed within intramedullary channel 414,middle phalanx 404 and proximal phalanx 406 are aligned with oneanother, drill 452 is disengaged from driving tube 600 and a drivinghandle similar to driving handle 300 illustrated in FIGS. 10-12.Specifically, trocar tip 710 and one or more flats 722 are receivedwithin an opening defined by the driving handle and engages the one ormore flats 722 disposed adjacent to trocar tip 710 on driver core 700.

The physician uses driving handle to rotate and drive implant 500, 800into proximal phalanx 406 due to the coupling between implant 500, 800,driving tube 600, and driver core 700. The clockwise rotation of threads510, 810 (or counterclockwise rotation depending the type of threads510, 810) advances implant 500, 800 into proximal phalanx 406 untilimplant engaging end 602 of driving tube 600 contacts proximal phalanx406. In some embodiments, a surgeon may feel when implant engaging endof driving tube 600 contacts the outermost surface of proximal phalanx406 since the outer diameter of driving tube 600 is greater than anouter diameter of threads 510, 810 of implant 500, 800. To provide afurther indication of proper insertion to the surgeon, the minordiameter of threads 510, 810 may increase in diameter such that thesurgeon will feel a greater resistance as implant 500, 800 is driveninto proximal phalanx 406 and the minor diameter engages the adjacentbone.

Once implant 500, 800 is disposed within proximal phalanx 406, theflexible portion 506, 806 of implant 500, 800 is deployed within distalphalanx 404 by decoupling implant 500, 800 from driving tube 600 anddriver core 700. FIGS. 27A-27C illustrate the relative positions of thefeatures of implant 500, 800, driving tube 600, and core 700 prior todecoupling and deployment of implant 500, 800 within proximal phalanx406. To decouple implant 500, 800 from driving tube 600 and driver core700, driver core 700 is rotated in an opposite direction (i.e., acounterclockwise direction), which results in dowel pin 720 beingdisengaged from extension 622-1 and being received within lengthwiseslot 620 (FIG. 28A) since driving tube 600 is held in place by virtue ofthe friction between the outer surface of driving tube 600 and theadjacent bone. The rotation of driver core 700 results in the rotationof implant 500, 800 due to the coupling between fin 706 of driver core700 and slot 516, 816 defined by implant 500, 800. The rotation ofdriver core 700 and implant 500, 800 results in only a slight backingout of implant 500, 800 due to the thread pitch of threads 510, 810being small.

With dowel pin 720 disengaged from extension 622-1, driver core 700 ispulled in an axial direction away from implant 500, 800 causing dowelpin 720 to slide along slot 620 until it contacts wall 624 that definesslot 620 as illustrated in FIG. 29A. The axial movement of driver core700 relative to tube 600 and implant 500, 800 results in blade 706 beingseparated from slots 516, 816 of implant 500, 800 as illustrated inFIGS. 29B and 29C since the axial movement of implant 500, 800 isconstrained by slot 612 of tube 600.

Driver core 700 is rotated in a clockwise direction such that dowel pin720 is received within extension 622-2 as illustrated in FIG. 30A.Further clockwise rotation of driver core 700 when dowel pin 700 isdisposed within extension 622-2 causes driving tube 600 to rotate in acounterclockwise direction forcing prominence 534 to cam along rampededge 626 of slot 612 (FIG. 30B) thereby separating implant 500, 800 fromits engagement with driving tube 600.

Driver core 700 is pulled axially out of intramedullary channel 414along with driving tube 600. Once implant engaging end 602 clears end518, 818 of implant 500, 808, prongs 514, 814 radially flex, such as theflexing of prongs 114 illustrated in FIG. 21, such that an edge 522 a ofanti-rotational feature 522, 822 engages the adjacent bone of middlephalanx 404. Body 802 of implant 800 will also flex such threadedportion 804 and flexible portion 806 are disposed at an angle withrespect to each other.

The retrograde installation technique described above advantageouslyenables the implant to fuse the DIP or PIP joints with improvedalignment of the phalanxes compared to the conventional antegradetechniques. Additionally the implant and implant system disclosed hereindo not have the drawbacks as the conventional implants and can beinstalled via the retrograde technique described above.

Although the systems and methods have been described in terms ofexemplary embodiments, they are not limited thereto. Rather, theappended claims should be construed broadly, to include other variantsand embodiments of the systems and methods, which may be made by thoseskilled in the art without departing from the scope and range ofequivalents of the systems and methods.

What is claimed is:
 1. An implant for fusing adjacent bones, comprising:an elongate threaded member; and a flexible portion extending from theelongate threaded member, the flexible portion including a plurality ofprongs configured to be reversibly compressed toward an axis defined bythe elongate threaded member.
 2. The implant of claim 1, furthercomprising: a projection radially extending from a body of the implantbetween the elongate threaded member and the flexible portion.
 3. Theimplant of claim 2, further comprising a plurality of projectionsradially extending from the body of the implant between the elongatethreaded member and the flexible portion.
 5. The implant of claim 1,wherein each of the prongs include a projecting edge extending in adirection that is approximately perpendicular with respect to thedirection in which the prong extends.
 6. The implant of claim 5, whereinthe implant has a circular cross sectional area.
 7. An implant system,comprising: an implant including an elongate threaded member, and aflexible portion extending from the elongate threaded member, theflexible portion including a plurality of prongs configured to bereversibly compressed toward an axis defined by the elongate threadedmember; a core pin for driving the implant into bone, the core pinincluding an elongate body having a pointed tip at one end and a finextending from an opposite end, the fin sized and configured to bereceived within a slot defined by the prongs of the implant; and a tubedefining a passageway extending from an implant engaging end to a corepin engaging end, the passageway sized and configured to receive theprongs of the implant and a first portion of the core pin therein. 8.The implant system of claim 7, wherein the implant includes a projectionradially extending from a body of the implant disposed between theelongate threaded member and the flexible portion.
 9. The implant systemof claim 8, wherein the implant engaging end of the tube defines a slotsized and configured to receive the projection radially extending fromthe implant therein.
 10. The implant system of claim 9, wherein the corepin engaging end of the tube defines a second slot that extends parallelto a longitudinal axis defined by the tube, the second slot sized andconfigured to receive a pin coupled to the core pin and including a pairof extensions that extend substantially perpendicular to thelongitudinal axis of the tube.
 11. The implant system of claim 10,wherein the fin is received within the slot defined by the prongs whenthe prongs and core pin are disposed within the passageway and the pinextending from the core pin is received within one of the extensions.12. A method of connecting adjacent bones, comprising: forming anincision to gain access to a joint between first and second bones;flexing the first and second bones such that the bones are disposed atan angle from one another; inserting a pointed tip of a core pinextending from a first end of a tube into a first end of a first boneuntil a tip of an elongate threaded member of an implant extending fromand at least partially disposed within a second end of the tube isreceived within an intramedullary channel formed by the core pin andtube, the first end of the first bone being closer to the second bonecompared to a second end of the first bone; repositioning the first andsecond bones such that they are approximately linearly aligned with eachother; rotating the core pin in a first direction to drive the elongatethreaded member into the second bone; decoupling the core pin from itsengagement with the implant; and withdrawing the core pin and tube fromthe first bone to disengage the second end of the tube from a flexibleportion of the implant including a plurality of prongs, wherein theplurality of prongs outwardly flex to contact the first bone whendisengaged from the second end of the tube.
 13. The method of claim 12,wherein decoupling the core pin from its engagement with the implantincludes: rotating the core pin relative to the tube in a seconddirection until a pin extending from an outer surface of the core pin isreceived within a slot defined by the tube, the slot extending in adirection that is approximately parallel to a lengthwise axis defined bythe tube; and moving the core pin along the lengthwise axis relative tothe tube such that a fin disposed at an end of the core pin that isopposite an end at which the pointed tip is disposed is moved out of aslot defined by the prongs of the implant.
 14. The method of claim 13,wherein the slot defined by the tube includes at least one extensionextending in an approximately perpendicular direction to a direction inwhich the slot extends.
 15. The method of claim 13, further comprising:rotating the core pin and tube in the first direction such that aprotrusion outwardly extending from the implant is disengaged with asecond slot defined by the tube.
 16. The method of claim 15, wherein thesecond slot defined by the tube is disposed adjacent to the second endof the tube.
 17. The method claim 12, wherein the core pin includes atleast one flat disposed along its length for being engaged by a tool.18. The method of claim 12, wherein withdrawing the core pin and tubefrom the first bone includes: rotating the core pin and tube in thedirection until a protrusion outwardly extending from the implant isdisengaged from a second slot defined by the tube; and pulling the corepin and tube out of the intramedullary channel.
 19. The method of claim12, wherein a first portion of the core pin that includes the pointedtip has a larger cross-sectional geometry than a second portion of thecore pin received within a passageway defined by the tube.
 20. Themethod of claim 19, wherein the second portion of the core pin includesa fin sized and configured to be received within a slot defined by theprongs of the implant.